The Compact Antenna Assembly generally relates to low frequency (LF) and high frequency (HF) antennas, and more particularly, relates to low and high frequency vertical antennas used for the radiation and reception of various radio frequency (RF) signals.
These antennas are typically used by operators of radio and video equipment in military, private and amateur radio sectors to transmit, receive or transmit and receive information. The compact antenna assembly utilizes a structure which significantly reduces the height and footprint of the antenna as compared to traditional vertically polarized antennas. The compact antenna assembly also provides the user the option of mounting the antenna on a clamped pipe to an existing mast or on the ground or flat rooftop with restricted installation real estate.
Conventional vertically polarized antennas are operated at heights equivalent of ¼ of a wavelength and require a large number of ¼ or greater radial leads dispersed from the antenna on or under the ground to perform efficiently. Proper construction and installation of these conventional antennas may operate at near 100% efficiency but require a very tall antenna and a very large radial counterpoise area. Moreover, a tall antenna must have lights at various heights, including at the top of the antenna unit to warn approaching aircraft of the tall antenna structure which is difficult for pilots to see while in flight. Furthermore these tall antennas are obstacles which inhibit aircraft such as jets taking off or landing on an aircraft carrier.
Previously, the need for a shorter vertically polarized antenna was addressed by installation of a coil of wire called an inductor between the top and bottom of the shortened antenna. The inductor effectively replaces the missing section of the antenna by ineffectively lengthening the antenna. As the antenna is shortened the inductor increases in size which results in lower antenna efficiency due to greater power dissipated in the larger coil. A decrease in antenna efficiency reduces the capability of the antenna to radiate or receive signals.
Until now, antenna science and technology have been unable to produce a short antenna with small horizontal installation real estate requirements which could perform as efficiently as a conventional ¼ wavelength counterpart and very large real estate consumption counterpoise counterpart. Particularly, as the conventional ¼ wavelength antenna is shortened and the size of the coil is increased, the electric field produced by the shortened antenna decreases while the magnetic field wasted by the coil increases, reducing the conventional antenna efficiency and qualities of transmission or reception.
The significance of the size of the electric field surrounding the antenna is directly related to antenna efficiency and quality of transmission or reception. Therefore, conventional short antennas with smaller surrounding electric energy are not effective in transmission or reception of electric fields due to wasted magnetic energy lost in the coils required to shorten them.
When current flows in an antenna it creates a magnetic field, H, surrounding the conductor or coil. This same current flow also creates an electric field, difference of potential, or voltage, E, between the emitter and counterpoise or ground radial system. The H and E fields interact or “cross” each other creating electro(E)-magnetic(H) radiation. Maxwell's equations indicate that the electromagnetic radiation resulting from E×H will be proportional to the smaller of these two quantities that are inherently balanced. Thus, as the coil size increases to shorten the antenna length, the magnetic energy wasted by the coil increases, reducing the antenna H field and thereby reducing the electromagnetic radiation produced by E×H.
As the vertical antenna is shortened, the radiation resistance decreases while antenna current increases, thereby increasing the antenna magnetic field (H). However, as an even larger coil is inserted to shorten the conventional antenna, the magnetic (H) field losses reduce the difference of potential (E) or voltage present above the coil (at the antenna feed point) and the antenna radiation produced by E×H. Thus, conventional attempts to reduce the height and width of vertically polarized antennas have not been successful in maintaining the efficiency of conventional ¼ wavelength vertically polarized antennas.
Conventional science and technology acknowledge peak performance from tall antennas. Those seeking optimum antenna performance must therefore suffer the adverse height and real estate consumption required by the conventional ¼ wavelength antenna or suffer the degradation in efficiency resulting from the installation of a conventional shortened vertical antenna having significant electromagnetic (E×H) losses.
In summary, there is substantial need for an antenna which requires much less height and installation real estate than either the conventional ¼ wavelength or the inefficient shortened version of the conventional ¼ wavelength antenna. If this can be accomplished, both installation and maintenance costs will be significantly reduced. The requirements for long counterpoise radial systems and aircraft lighting beacons will be eliminated. The possibility to install compact and effective antennas in restricted areas will be available when magnetic field (H) losses can be eliminated from conventional vertically polarized antennas.